The present invention relates to a device, equipment and apparatus for mechanically operating a cargo hatch or baggage or freight door in an aircraft particularly for swinging it open and out.
Freight hatches, cargo doors and hatches of the kind to which the invention pertains are usually quite large and, relatively speaking, quite heavy. It is therefore customary to use electromotors for opening them and closing them. For example, European patent 105082 and PCTWO84/01761 suggest devices for operating freight hatches, and cargo doors in aircraft wherein, under utilization of an electromotor lever linkage causes the hatch, gate or door to be forced out of the fuselage and up, for opening same. Such electromotor driven opening devices and structures have offered the advantage that any manual power and energy is not needed for opening the hatch door or gate in an automatic fashion. Of course devices of this kind are inherently disadvantaged by the fact that they depend on a functioning and operating electric power supply. Moreover, as compared with strictly mechanical opening and closing devices for such doors and hatches, motor driven devices are relatively heavy. Inherent of course in the automation is also that they are prone to breakdown. That in turn requires additional drives possibly redundancy, monitoring control structure and so forth.
U.S. Pat. No. 4,601,446 describes a manually operated opening device and structure for cargo hatches whereby however the gate or door opens into the interior of the craft. A spring guided and biased weight balancing and compensating mechanism insures that opening and closing of the hatches is fairly easy. Also a certain attenuation is provided for to make sure that particularly closing of the gate is attenuated towards a more or less gentle final closing stage.
Mechanical devices of this kind are disadvantaged by a very complex mechanism as far as adjustment and actuation is concerned. Moreover, this particular mechanism is suitable only for opening the gate towards the inside and not for having it swing out. The path involved is totally different. Similar disadvantages are offered by the somewhat older U.S. Pat. No. 3,773,311 for the access door to baggage space and compartments in aircraft. Also here a spring attenuating system makes sure that the inwardly opening gate is movable at a constant actuating force.
Finally German printed patent application 3,608,735 (corresponding to U.S. Pat. No. 4,787,578) is mentioned wherein a mechanically actuated opening device is provided for a freight hatch which swings inwardly. Opening structure has a torsion rod which is capable of taking up the weight of the gate over the entire range.